This invention may be applied to the following technology fields, WiFi and WiMAX network technology, 3GPP LTE (Long Term Evolution) network technology, and future network technology beyond the mentioned one.
WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides for the wireless transmission of data using a plurality of transmission modes, from point-to-point links to portable internet access. The technology is based on the IEEE 802.16 standards.
3GPP LTE (Long Term Evolution) is the name to a project within the Third Generation Partnership Project to cope with future technology evolutions. Goals include improving spectral efficiency, lowering costs, improving services, making use of new spectrum and refarmed spectrum opportunities, and better integration with other open standards. The LTE architecture is called EPS (Evolved Packet System) and comprises E-UTRAN (Evolved UMTS Terrestrial Radio Access Network) on the access side and EPC (Evolved Packet Core) on the core side. The LTE access network may consist of eNB (E-UTRAN Node B) nodes providing all radio interface related functions. The LTE core network may consists of the nodes S-GW (Serving Gateway) routing and forwarding user data packets, the nodes P-GW (PDN (Public Data Network) gateway) providing connectivity between the user equipment and the external packet data networks, MME (Mobile Management Entity) providing control functions for the LTE access network such as User Equipment identity, part of mobility, and security functions.
It has become an important topic for wireless cellular communication such as WiMAX and LTE to integrate multi-hop capability by deploying relay stations (RS).
Mobile WiMAX System standard is being standardized in WiMAX Forum. The Forum uses the broadband radio interface standardized by IEEE 802.16-2004 with a mobility amendment IEEE 802.16e-2005. The Forum specifies standard for network system architecture for mobile & portable terminals to access the Internet and operator services. Currently, a revision of the radio standard, IEEE 802.16-2009, issues.
Within the IEEE 802 LAN/MAN Standards Committee, a Broadband Wireless Access Working Group 802.16, Mobile Multihop Relay Task Group J (802.16j), has developed an amendment to the radio standards 802.16-2004, and 802.16e-2005. Currently a revision is standardized. The amendment standardizes the functionality of a relay station. A relay station is a radio station that receives the signal from 802.16j defined Multihop-Relay Base Station, further processes and amplifies it and re-transmits it towards the mobile stations that follow the 802.16-2009 protocol, and performs corresponding function for the signal in the opposite direction. The function of the relay station is completely transparent to the mobile station.
This invention is addressing the problem of the topology information distribution in a network example given supporting relay stations even in cases when the relay station has moved.
This invention is also addressing the problem of the topology information distribution in networks supporting femtocells. A femtocell is a small cellular base station, typically designed for use in residential or small business environments. It allows service providers to extend service coverage indoors. The concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA and WiMAX solutions. The distribution of topology information may be needed since the femtocell nodes may be transported to any location and attached to the network with no guarantees that it can be connected to the same gateway as during previous attachment. In this manner the WiMAX femto base stations may be transported to another Access Service Network gateway. An HNB Access Network comprises the two network element types Home Node B (HNB), and the Home Node B Gateway (HNB-GW).
The Home Node B provides 3G radio coverage for 3G handsets within a home location. The Home Node B Gateway (HNB-GW) is installed within an operator's network, and aggregates traffic from a large number of Home Node Bs back into an existing core service network through the standard interfaces.
The relay stations appear to the mobile stations like a base station, e.g. they may have the same type of identity designation (Base station identity, BSID) as the base station, but not performing all the functionalities of a base station. The way how functionalities are split between the base station and relay station can vary depending on the chosen options according to the 16j standard. The base station controls the operation of one or several relay stations assigned to it, and operates as a grooming point for the information traffic to or from the mobile stations via the relay stations that are directly transmitting to or from the mobile stations. The relay station may have other relay stations assigned to it, so that there may be a tree structure of relay stations dependent on a base station.
A relay station may perform a handover to a new base station, and may take all the attached mobile stations with it. Thus the topology of the network with relay stations may change dynamically. Similarly, a femto base station can be transported to any location and there is no guarantee that it will attach to the same gateway as before. Thus the topology of the network with femto base stations may change dynamically. The base station identifier used by mobile station, may relate to other base stations or relay stations as they are visible to the mobile station(s).
To accommodate relay stations in WIMAX two specific problems have to be addressed which are described below.
There is a procedure called association in the IEEE 802.16e radio standard. This procedure enables the mobile station to collect information about the surrounding base stations or relay stations, for example to estimate the radio path loss or signal to interference ratio for these elements (base station or relay station), while still being attached (registered) to the serving base station. The association procedure includes a ranging function, where the mobile station sends a short standardized bit sequence to the target element, and the element answers and tells, e.g., the power level, quality and time offset of the received sequence. The serving Base Station will send a request to organize a dedicated ranging resource at specified time and frequency (frequency in terms of sub channel) so that the associated base station can immediately recognize that it is the specified terminal that sent the ranging sequence. There is the request to find the right access points such as base stations or relay stations, sending messages.
Another similar need is for the hand-over purpose. In the preparation phase of a hand-over the serving base station and mobile Station agree about the new serving element, base station or relay station. In fact the mobile station is registered to the base station but the immediate serving transmitter may be a relay station, which has an identifier (BSID), so from the physical radio connectivity point of view the terminal communicates with the relay station.
The task of this invention may to provide a telecommunication network having a plurality of access nodes and a plurality of gateway nodes, with network topology information allowing full operation without restriction even in cases when the concerned access node such as base station or relay station has moved.